Warm air furnace

ABSTRACT

A warm air furnace prevents household articles from freezing in the case where combustion is discontinued due to lack of gas during combustion operation when a house is emptied. The warm air furnace is equipped with a retry operation controller  33  which carries out ignition action of a combustor  5 , in the case where a predetermined period of time lapsed from the time it is determined that combustion at the combustor  5  is discontinued during combustion operation by a combustion operation controller which controls operation of the combustor, determines whether or not combustion at the combustor  5  is started, and repeats the ignition action for igniting the combustor  5  until it is determined that combustion at the combustor  5  is started, in the case where a predetermined time lapsed from the time it is determined that the combustion at the combustor  5  is not started.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a warm air furnace having a combustion operation control function which carries out an ignition action again in the case where combustion is discontinued during combustion operation due to lack of gas.

2. Description of the Related Art

Conventionally, as the type of the warm air furnace explained above, there is known a combustion appliance equipped with a burner for combusting a liquid fuel, a fuel supplier for supplying the fuel to the burner, a fuel detector for detecting existence or nonexistence of the fuel, and a combustion control unit which controls the fuel supplier and makes the burner carry out combustion, wherein the combustion appliance carries out an ignition action again in the case where combustion is discontinued during combustion operation due to lack of gas (refer to Japanese patent laid-open No. H09-280558).

This combustion appliance is a combustion appliance which temporarily stops the combustion with a signal from the fuel detector indicating nonexistence of fuel, and starts counting of a predetermined period of time by a timer. When a signal from the fuel detector indicating existence of fuel is received within a predetermined period of time, the combustion appliance automatically restarts combustion. After lapse of the predetermined period of time, the combustion appliance does not restart combustion even when the signal from the fuel detector indicating existence of fuel is received.

In the conventional combustion appliance, combustion is not restarted after lapse of the predetermined period of time even when the signal from the fuel detector indicating existence of fuel is received, so that there is a problem that room temperature drops and household articles freezes when a house in frigid climate is emptied for a long period of time.

SUMMARY OF THE INVENTION

In view of such circumstances, an object of the present invention is to provide a warm air furnace capable of preventing household articles from freezing in the case where combustion is discontinued during combustion operation due to lack of gas when a house is emptied.

In order to achieve the above object, the present invention provides a warm air furnace comprising an air intake which takes in air; a combustor which is supplied with air taken in by the air intake and the fuel gas, and which combusts the same; an exhauster which exhausts a combustion gas combusted at the combustor to outdoors; a heat exchanger which is provided at the exhauster and which is for conducting heat of the combustion gas to indoor air; an air blower which blows the indoor air so as to receive heat from the heat exchanger; a combustion operation controller which controls operation of the combustor; and a retry operation controller which carries out the ignition action of the combustor in the case where a predetermined period of time lapsed from the time it is determined that the combustion at the combustor is discontinued during combustion operation by the combustion operation controller, determines whether or not the combustion at the combustor is started, and repeats the ignition action of igniting the combustor, in the case where it is determined that the predetermined period of time lapsed from the time it is determined that the combustion at the combustor is not started, until it is determined that the combustion at the combustor is started.

According to the present invention, the warm air furnace includes the retry operation controller which repeats the action of igniting the combustor until it is determined that the combustion is started at the combustor in the case where the predetermined time lapsed from the time it is determined that the combustion is discontinued at the combustor during combustion operation by the combustion operating controller, so that in the case where the combustion is discontinued due to lack of gas during combustion operation in an emptied house in frigid climate, the combustion operation is restarted when the fuel is supplied. By doing so, it becomes possible to prevent the household articles from freezing.

In the warm air furnace of the present invention, the retry operation controller carries out the ignition action of igniting the combustor in the case where a difference between a target room temperature set by a room temperature setting switch and a detected room temperature detected by a room temperature sensor becomes equal to or more than a predetermined temperature, and the predetermined time lapses.

According to the present invention, it becomes possible to ignite the combustor in order to prevent the household articles from freezing, in the case where the predetermined period of time lapsed after the detected temperature drops greatly (exceeding the predetermined temperature difference) below the target room temperature.

In the warm air furnace of the present invention, the air intake is comprised of an air intake tube which takes in outdoor air. According to the present invention, it is possible to apply the same to a forced flue type warm air furnace which takes in outdoor air.

Or, in the warm air furnace of the present invention, the air intake is comprised of an air intake tube which takes in indoor air. According to the present invention, it is possible to apply the same to a closed flue type warm air furnace which takes in indoor air.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system configuration view of an example of a warm air furnace according to the present invention;

FIG. 2 is a control block diagram of the warm air furnace shown in FIG. 1; and

FIG. 3 is a flow chart showing a retry operation control process in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1, a warm air furnace is for example a forced flue type gas warm air furnace. A main body case 1 of the warm air furnace arranged inside a room is equipped at the interior thereof with an air blow flue 2, an air blow fan 3 which is an air blower for convecting indoor air via the air blow flue 2, and a combustion device main body 4 for heating the indoor air flowing through the air blow flue 2.

The combustion device main body 4 is equipped with a burner 5 which is a combustor, a combustion chamber 6 accommodating the burner 5, and a heat exchanger 7 which is a thermal exchanger continuing to the combustion chamber 6.

The combustion chamber 6 is connected with an air intake tube 8 for combustion air, and is also connected with an exhaust tube 9 which is an exhauster of combustion exhaust via the heat exchanger 7. The air intake tube 8 and the exhaust tube 9 are extended to the outside of the main body case 1, and are lead out outdoors.

The air intake tube 8 is provided with a combustion fan 10 for supplying combustion air to the burner 5 inside the combustion chamber 6. The combustion fan 10 is configured from a rotary vane 11 provided inside the air intake tube 8 so as to be able to rotate freely, and a combustion fan motor 12 for rotary driving the rotary vane 11. The air intake tube 8 and the combustion fan 10 constitute the air intake of the present invention.

The burner 5 inside the combustion chamber 6 is connected to a gas supply pipe 13 introduced from outside of the main body case 1, and the fuel gas supplied from the gas supply pipe 13 is mixed with the combustion air introduced into the combustion chamber 6 from the air intake tube 8, so as to combust the air-fuel mixture.

In the combustion chamber 6, an ignition electrode 14 for igniting the burner 5 and a flame detector 15 such as a flame rod or a thermocouple for detecting flame of the burner 5 are provided facing the burner 5.

The gas supply pipe 13 is disposed with two on-off solenoid valves 16, 17, and a gas proportional valve 18.

The air blow flue 2 includes an air inlet 19 and an air outlet 20 at the rear surface and the front surface of the main body case 1, respectively, and is formed through the heat exchanger 7 in between the air inlet 19 and the air outlet 20. The air inlet 19 is mounted with an air filter 21, and the air outlet 20 is fixed with a louver 22 for adjusting the direction of blowout of the warm air.

The air blow fan 3 is configured from a rotary vane 24 provided inside the air blow flue 2 facing the air inlet 19 of the air blow flue 2, and an air blow fan motor 25 for rotary driving the rotary vane 24. The air blow fan 3 takes in indoor air into the air blow flue 2 by the rotation of the rotary vane 24 via the air inlet 19. Then, the air blow fan 3 flow the air taken into the air blow flue 2 towards the air outlet 20 within the air blow flue 2 via the heat exchanger 7, and blows out the air into the room from the air outlet 20.

The air blow flue 2 is provided with a room temperature sensor 26 which detects the temperature of the indoor air taken in by the air blow fan 3 as the room temperature at a position facing the air inlet 19.

As shown in FIG. 1 and FIG. 2, the gas warm air furnace of the present embodiment is equipped with a controller 27 which carries out operation control via the solenoid valves 16, 17, the gas proportional valve 18, the combustion fan motor 12, the air blow fan motor 25, and the ignition electrode 14, an operation switch 28 for the user to instruct on/off of operation, a retry operation setting switch 29 for setting execution of a retry operation to be explained later, and a manipulating device 31 including a room temperature setting switch 30 for setting a target room temperature for combustion operation and the like.

As shown in FIG. 2, the controller 27 is equipped with, as means for realizing the functions according to the present invention, a combustion operation controller 32 (this includes a retry operation controller 33 described later), and a temperature adjustment controller 34.

The combustion operation controller 32 carries out control of the combustion operation, when operation start is instructed by the operation switch 28, on the basis of a combustion amount determined at the temperature adjustment controller 34.

As such, the temperature adjustment controller 34 is equipped with a combustion amount determining unit 35. The combustion amount determining unit 35 determines the combustion amount (heating amount) of the burner 5 on the basis of the difference between the target room temperature and the detected temperature detected by the room temperature sensor 26, while taking the temperature set by the room temperature setting switch 30 as the target room temperature.

That is, the combustion amount determining unit 35 momentarily obtains the necessary combustion amount of the burner 5, on the basis of the difference between the detected temperature by the room temperature sensor 26 and the set room temperature for combustion operation (target room temperature during combustion operation) by the room temperature setting switch 30.

The combustion operation controller 32 controls the supply amount of the fuel gas and the combustion air to the burner 5 via the gas proportional valve 18 and the combustion fan motor 12, respectively, so as to make the burner 5 combust at the necessary combustion amount.

At this time, the combustion amount determining unit 35 carries out the temperature adjustment operation of the warm air furnace by controlling the air blow fan motor 25 so that an air volume of the air blow fan 3 according to the necessary combustion amount of the burner 5 is obtained.

Further, the combustion operation controller 32 may carry out a forced high operation in which combustion operation with comparatively high heat quantity is executed forcibly, and a forced low operation in which combustion operation with comparatively low heat quantity is executed forcibly.

The retry operation controller 33 carries out control to retry the ignition action each time after lapse of a predetermined period of time until the fuel gas is supplied, in the case where the operation start is instructed by the retry operation setting switch 29 and the combustion is discontinued during combustion operation due to lack of fuel gas.

Next, the actuation of the warm air furnace according to the present embodiment will be explained.

First, a brief explanation will be given on the basic action during combustion operation, with reference to FIG. 1 and FIG. 2. A predetermined target room temperature is preliminarily set by the room temperature setting switch 30 before combustion operation.

When the operation start instruction is given by the user turning on the operation switch 28, the controller 27 actuates the combustion fan 10, and then makes the ignition electrode 14 generate spark discharge for a predetermined period of time, as well as opens the solenoid valves 16, 17 and the gas proportional valve 18 of the gas supply pipe 13 to start supply of a predetermined amount of fuel gas to the burner 5. Thereby, ignition process of the burner 5 is carried out. Thereafter, ignition of the burner 5 is confirmed by the flame detector 15.

After performing ignition of the burner 5 as is explained above, the controller 27 controls the air blow fan motor 25 so as to actuate the air blow fan 3. Accordingly, indoor air is taken in to the air blow flue 2 via the air inlet 21.

The air taken in is heated via the heat exchanger 7, which is heated by the combustion heat of the burner 5, during flowing through the air blow flue 2 towards the air outlet 20, and is blown out from the air outlet 20 as a warm air.

When the combustion at the burner 5 and the actuation of the air blow fan 3 are started, the temperature adjustment controller 34 determines the combustion amount of the burner 5 according to the difference between the detected temperature of the room temperature sensor 26 and the target room temperature as described above, and the combustion operation controller 32 controls the combustion action of the burner 5 and the air volume of the air blow fan 3. By doing so, the temperature adjustment control is carried out.

In the temperature adjustment control, basically, the combustion amount of the burner 5 is decreased, and the air volume of the warm air is decreased by lowering the rotation speed of the air blow fan 3, as the detected room temperature by the room temperature sensor 26 approaches the target room temperature.

If the detected temperature by the room temperature sensor 26 becomes lower than the target room temperature, from the change in the target room temperature and the like, the combustion amount of the burner 5 is increased, and the air volume of the warm air is increased by raising the rotation speed of the air blow fan 3.

If the operation switch 28 is turned off during such combustion operation, the combustion operation is stopped, the solenoid valves 16, 17 and the gas proportional valve 18 of the gas supply pipe 13 are closed to stop the supply of the fuel gas to the burner 5, the fire at the burner 5 is extinguished, and the combustion fan 10 and the air blow fan 3 are stopped.

The action explained above is the basic action during the combustion operation of the warm air furnace according to the present embodiment. Further, in the warm air furnace of the present embodiment, the controller 27 executes the retry operation control process to be explained hereinafter by the combustion operation controller 32 including the retry operation controller 33.

As is shown in FIG. 3, first, the controller 27 carries out the temperature adjustment operation with the combustion operation controller 32 and the temperature adjustment controller 34 (STEP 1). Thereafter, whether or not the combustion at the burner 5 is discontinued during the temperature adjustment operation is determined on the basis of the output of the flame detector 15 which detects the flame of the burner 5 (STEP 2).

Then, in the case where the determination result in STEP 2 is NO (in the case where the combustion at the burner 5 is not discontinued during temperature adjustment operation), the combustion operation controller 32 continues the temperature adjustment operation. On the other hand, in the case where the determination result in STEP 2 is YES (in the case where the combustion at the burner 5 is discontinued during temperature adjustment operation), the combustion operation controller 32 stops the temperature adjustment operation (STEP 3). That is, the combustion operation controller 32 closes the solenoid valves 16, 17 and the gas proportional valve 18 of the gas supply pipe 13 to stop the supply of the fuel gas to the burner 5, extinguishes the fire at the burner 5, and stops the combustion fan 10 and the air blow fan 3.

Then, it is determined whether or not the difference between the target room temperature set by the room temperature setting switch 30 and the detected room temperature detected by the room temperature sensor 26 is equal to or more than a predetermined temperature (N° C.) (STEP 4).

In the case where the determination result in STEP 4 is NO (in the case where the difference between the target room temperature set by the room temperature setting switch 30 and the detected room temperature detected by the room temperature sensor 26 is not equal to or more than the predetermined temperature), the warm air furnace stands by until the difference between the target room temperature set by the room temperature setting switch 30 and the detected room temperature detected by the room temperature sensor 26 becomes equal to or more than the predetermined temperature.

On the other hand, in the case where the determination result in STEP 4 is YES (in the case where the difference between the target room temperature set by the room temperature setting switch 30 and the detected room temperature detected by the room temperature sensor 26 is equal to or more than the predetermined temperature), the combustion operation is started as is explained hereinbelow.

That is, the controller 27 carries out an ignition action for igniting the burner 5 with the ignition electrode 14, by actuating the combustion fan 10, making the ignition electrode 14 generate spark discharge for a predetermined period of time, and starting the supply of fuel gas of a predetermined amount to the burner 5 by opening the solenoid valves 16, 17 and the gas proportional valve 18 of the gas supply pipe 13 (STEP 5). Further, the controller 27 starts actuation of the air blow fan 3 by controlling the air blow fan motor 25.

Then, the controller 27 determines whether or not the combustion is started at the burner 5 by the ignition action, on the basis of the output of the flame detector 15 which detects the flame of the burner 5 (STEP 6).

Thereafter, in the case where the determination result in STEP 6 is YES (in the case where combustion is started at the burner 5 with the ignition action), the controller 27 carries out the forced high operation with the combustion operation controller 32 (STEP 7). On the other hand, in the case where the determination result in STEP 6 is NO (in the case where the combustion at the burner 5 is not started by the ignition action), the controller 27 carries out the retry action of the ignition action.

Next, the controller 27 determines whether or not the discontinuation of combustion occurred during the forced high operation, on the basis of the output of the flame detector 15 which detects the flame of the burner 5 (STEP 8).

Then, in the case where the determination result in STEP 8 is NO (in the case where the combustion at the burner 5 is not discontinued during the forced high operation), the controller 27 returns to STEP 1 and carries out the temperature adjustment operation. In the case where the determination result in STEP 8 is YES (in the case where the combustion at the burner 5 is discontinued during the forced high operation), the controller 27 carries out the ignition action of igniting the burner 5 with the ignition electrode 14 (STEP 9).

Thereafter, the controller 27 determines whether or not the combustion at the burner 5 is started by the ignition action, on the basis of the output of the flame detector 15 which detects the flame of the burner 5 (STEP 10).

Next, in the case where the determination result in STEP 10 is YES (in the case where the combustion at the burner 5 is started by the ignition action), the controller 27 continues the forced high operation. On the other hand, in the case where the determination result in STEP 10 is NO (in the case where the combustion at the burner 5 is not started with the ignition action), the controller 27 carries out the retry action of the ignition action. First, the controller 27 determines whether or not a predetermined period of time has lapsed from the ignition action (STEP 11).

Then, in the case where the determination result in STEP 11 is NO (in the case where the predetermined period of time had not lapsed from the ignition action), the controller 27 waits until the predetermined period of time lapses from the ignition action. On the other hand, in the case where the determination result in STEP 11 is YES (in the case where the predetermined period of time lapsed from the ignition action), the controller 27 carries out the ignition action of igniting the burner 5 with the ignition electrode 14 (STEP 12).

Thereafter, the controller 27 determines whether or not the combustion at the burner 5 is started by the ignition action, on the basis of the output of the flame detector 15 which detects the flame of the burner 5 (STEP 13).

Then, in the case where the determination result in STEP 13 is NO (in the case where the combustion at the burner 5 is not started with ignition action), the controller 27 returns to STEP 11, and determines again whether the predetermined period of time has lapsed from the previous ignition action. On the other hand, in the case where the determination result in STEP 13 is YES (in the case where the combustion at the burner 5 is started with ignition action), the controller 27 carries out the forced high operation.

Thereafter, the controller 27 repeats the processing of STEP 11 through STEP 13, until the determination result in STEP 13 becomes YES (until the combustion at the burner 5 is started by the ignition action).

In the processing explained above, the processing in STEP 2 and STEP 8 corresponds to the determination on discontinuation of combustion of the present invention. Further, the processing in STEP 5, STEP 9 and STEP 12 corresponds to the ignition action of the present invention. Still further, the processing in STEP 11 corresponds to the determination on lapse of predetermined period of time of the present invention. Still further, the processing in STEP 6, STEP 10, and STEP 13 corresponds to the determination on start of combustion of the present invention. The repeating of the processing in STEP 11 through STEP 13 corresponds to the retry operation control of the present invention.

As is explained above, according to the present embodiment, the controller 27 carries out the processing of determining whether or not the predetermined period of time had lapsed after it is determined that combustion did not start until it is determined that combustion is started. Thereafter, by carrying out the retry operation control of repeating the ignition action in the case where it is determined that the predetermined period of time had lapsed, the combustion operation is restarted when the fuel gas is supplied, so that it is possible to prevent household articles from freezing when a house in frigid climate is emptied even in the case where the combustion at the burner 5 is extinguished due to lack of fuel gas during combustion operation.

In the above-explained embodiment, explanation is given to a forced flue type warm air furnace which takes in combustion air from outdoors with a combustion fan and forcibly exhausting to the outdoors. However, the present invention is not limited thereto. The present invention may be applied to a forced exhaust type warm air furnace which takes in combustion air from indoors and forcibly exhausts to outdoors with an air blower, or a closed flue system type warm air furnace which takes in combustion air from indoors and exhaust to the outdoors by a natural aeration force with an exhaust stack. Moreover, the present invention may be applied not only to a warm air furnace using gas fuel but also to a warm air furnace using liquid fuel.

Further, the present invention is not limited to a combustion type warm air furnace, and it is possible to obtain a similar effect by applying the retry operation control of the present invention as long as it is a warm air furnace including a heat exchanger. 

1. A warm air furnace which carries out an ignition action again in the case where combustion discontinues due to lack of fuel gas during combustion operation, comprising: an air intake which takes in air; a combustor which is supplied with air taken in by the air intake and the fuel gas, and which combusts the same; an exhauster which exhausts a combustion gas combusted at the combustor to outdoors; a heat exchanger which is provided at the exhauster and which is for conducting heat of the combustion gas to indoor air; an air blower which blows the indoor air so as to receive heat from the heat exchanger; a combustion operation controller which controls operation of the combustor; and a retry operation controller which carries out the ignition action of the combustor in the case where a predetermined period of time lapsed from the time it is determined that the combustion at the combustor is discontinued during combustion operation by the combustion operation controller, determines whether or not the combustion at the combustor is started, and repeats the ignition action of igniting the combustor, in the case where it is determined that the predetermined period of time lapsed from the time it is determined that the combustion at the combustor is not started, until it is determined that the combustion at the combustor is started.
 2. The warm air furnace according to claim 1, wherein the retry operation controller carries out the ignition action of igniting the combustor in the case where a difference between a target room temperature set by a room temperature setting switch and a detected room temperature detected by a room temperature sensor becomes equal to or more than a predetermined temperature, and the predetermined time lapses.
 3. The warm air furnace according to claim 1, wherein the air intake is comprised of an air intake tube which takes in outdoor air.
 4. The warm air furnace according to claim 1, wherein the air intake is comprised of an air intake tube which takes in indoor air. 